Reversible Vascular Filter Devices and Methods for Using Same

ABSTRACT

The present invention provides, in one embodiment, a vascular filter device for capturing dislodged blood clots within a vessel. The vascular filter device includes an expandable framework for securing the device within a vessel. The device also a pathway extending through the framework. The device further includes at least one filter in alignment with the pathway for capturing dislodged clots or emboli. In an embodiment, the filter can be given form by a material that can be easily eliminated in situ to permit reestablishment of the pathway.

RELATED APPLICATIONS

The present application claims priority to and benefits of Provisional Application No. 61/289,508 filed Dec. 23, 2009, Provisional Application No. 61/295,457 filed Jan. 15, 2010, Provisional Application No. 61/304,155 filed Feb. 12, 2010, and Provisional Application No. 61/314,816 filed Mar. 17, 2010, the disclosures of all of which applications are incorporated herein by reference in their entirety.

TECHNICAL FIELD

This invention relates generally to intravascular devices and more particularly to filter devices implantable within the vena cava for capturing dislodged clots or debris.

BACKGROUND ART

Vena caval filters can be utilized in conjunction with anti-coagulants and thrombolytic agents to prevent pulmonary embolism and other vascular diseases from occurring within the body. These devices are generally implanted within a vessel, such as the inferior vena cava, to capture dislodged blood clots (emboli) contained in the blood stream. If a blood clot forms in the deep veins of a lower extremity and dislodges, the blood clot may proceed up the vena cava into the heart and into the pulmonary arteries, where it may block and interrupt blood flow. Mortality is typically high in the event of pulmonary embolism.

Filtering devices that are placed in the vena cava have been available for a number of years. Various vena caval filters have been developed over the years, including the Mobin-Uddin umbrella filter, introduced in 1967 and discontinued in 1986. The Greenfield vena caval filter has been in wide use for a number of years and is known as the standard in vena caval filters.

To trap emboli, many conventional vena caval filters employ several independent filter legs that can be expanded within the vessel to form a substantially conical-shaped filtering profile within which emboli or clots can be collected. To prevent migration of the filter within the vessel, a hook, barb or other piercing or anchoring mechanisms on the filter leg can be used to secure the filter to the wall of the vena cava. For example, the Greenfield filter has multiple legs meeting at a central apex and has attachment hooks on the legs. Deployment of the Greenfield filter often occurs in a tilted fashion, which decreases clot capture ability of the filter. Moreover, the Greenfield filter is placed in the vessel in one direction that funnels clots to the apex of the filter and the center of the vessel. In addition, the attachment hooks on the legs of the Greenfield filter are also uni-directional and positioned for funneling clot to the apex of the filter. Thus, continued use of the Greenfield filter in the vessel may lead to accumulation of clots near the apex of the filter, and may further block and interrupt blood flow near the center of the vessel.

Furthermore, it should be noted that a percentage of patients only need a vena caval filter as protection from a pulmonary embolism for a short period of time. As such, leaving an implantable filter in place for an extended period of time may lead to complications, including inferior vena cava thrombosis, deep venous thrombosis, filter migration, and vena cava perforation. Therefore, in some circumstances, it may be desirable to remove the filter from the patient.

Removal of the filter from the vena cava, however, is met with certain hurdles. For example, some of these filters may not be easily removable from a patient due to fibrous in-growth into the filter. In particular, after deployment of a filter in a patient, proliferating intimal cells can start accumulating around the filter framework in contact with the wall of the vessel. After a length of time, such accumulation or in-growth can prevent removal of the filter without risk of trauma, requiring the filter to remain in the patient.

Another hurdle to removing a filter from the vena cava results from conventional vena caval filters becoming off-centered or tilted with respect to the hub of the filter as well as the longitudinal axis of the vessel within which the filter is situated. Removal of an off-centered or tilted filter can be difficult as the barbs or hooks securing the filter in place can dig further into the vessel walls and act to injure or damage the vessel during removal.

Accordingly, it would be desirable to have an effective vena caval filter that can be eliminated after the underlying condition has passed, while avoiding damaging the tissue of the vessel wall within which the filter is located.

SUMMARY OF THE INVENTION

The present invention provides, in one embodiment, a bi-directional filter device for capturing undesirable materials. The filter device includes an expandable framework for secured placement of the device against a wall of a vessel. In certain embodiments, the framework can include an attachment mechanism to enhance secured placement of the device against the wall of the vessel. The filter device can also include a pathway extending through the expandable framework. In an embodiment, opposing filters may be situated within the pathway, each defined by a plurality of malleable legs capable of being moved by an external force between a position where the plurality of legs are substantially against the framework and a position where the plurality of legs approximate a substantially conical configuration. In one embodiment, the legs of the opposing filters, when approximating the substantially conical configuration, can act to capture undesirable materials flowing through the vessel. The legs of the opposing filters can also be sufficiently spaced apart to capture undesirable materials of a predetermined size. In addition, the legs of one filter can be offset from the legs of the opposing filter, so that should an undesirable material flowing through the framework escapes the legs of one filter, that escaping undesirable material can be captured by the legs of the opposing filter. In various embodiments, the legs of the opposing filters may be designed to direct the undesirable materials captured thereon along a predetermined path. The legs of the opposing filters can also be designed such that where undesirable materials are on the legs of both opposing filters, a fluid pathway still exists through the pathway of the framework. In addition, the plurality of legs when positioned substantially against the framework can allow the framework to be in one of a collapsed position, or an expanded position that can establish a substantially tubular pathway through the framework. In certain embodiments, the external force acting on the plurality of legs can be a balloon catheter designed to extend through the framework to move the plurality of legs.

The present invention also provides a method for capturing an undesirable material. The method includes, initially placing, within a vessel at a site of interest, a framework having a plurality of malleable legs coupled to a proximal portion and a set of malleable legs coupled to a distal portion of the framework. Next, an external force may be exerted within the framework so as to permit the plurality of legs at the proximal portion and the distal portion of the framework to approximate opposing substantially conical configurations to act as opposing filters. Thereafter, the external force may continue to be exerted within the framework to secure the expandable framework against a wall of the vessel. Once secured, undesirable material may be allowed to flow into the framework to permit the undesirable material to be captured by the legs of at least one of the opposing filters. In one embodiment, an undesirable material flowing through the framework that escapes the legs of one filter can be captured by the legs of the opposing filter. The method can further include pushing the plurality of legs of the opposing filters from a conical configuration against the framework to establish a substantially tubular pathway through the framework, once filtering is no longer needed.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A-1C show still another bidirectional vascular filter device in accordance with one embodiment of the present invention.

FIGS. 2A-2D show still another bidirectional vascular filter device in accordance with one embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

As used herein, in addition to the other terms defined in this disclosure, the following terms may have the following meanings:

“Arms” or “legs” means an elongated member or a slender part extending from a proximal end to a distal end.

“Bidirectional” means a filter device that can be used in two opposing directions; i.e., either end can allow a fluid to flow through the filter while capturing undesirable materials. “Uni-directional” or “one-directional” means a filter device that can be used in one direction only; i.e., a fluid can flow through the filter from one end to the other only while capturing undesirable materials.

“Blood clots”, “clots”, “emboli” and “debris” refers to substances found within blood flow that can be filtered using the vascular filter device of the present invention. They can have various profiles (e.g., from substantially stringy to substantially globular) and sizes (e.g., from less than 1 mm to a few centimeters). “Blood clots”, “clots”, “emboli” and “debris” can be used interchangeably through the application. Collectively, they can be referred to as “undesirable materials.”

“Collapsed” or “constricted” means that at least a portion of a filter device is in a non-expanded position. The filter device or a portion thereof would normally be in a collapsed or constricted position when introduced into a vessel and/or when retained within a cover sheath of a triaxial catheter.

“Criss-cross” pattern means a wire pattern wherein the wires cross one another.

“Device”, “filter device” or “vascular filter device” means a structure for filtering in one or more vessels.

“Diameter” as used in connection with a vessel means the approximate diameter of a vessel since vessels are not often perfectly cylindrical. “Diameter” as used with respect to any structure means an approximate diameter.

“Dilated” means enlarged or expanded in width, bulk or extent.

“Expanded” means that at least a portion of a vascular filter device is in an expanded position. A vascular filter device or a portion thereof within a vessel may be expanded for the purpose of allowing fluid to substantially freely flow through the vessel. “Expanded” and “substantially expanded” may be used interchangeably when used in connection with a filtration device. “Self-expanding” means a filter device capable of expanding on its own, without external forces.

“Filter” means a device or structure having the function of holding back or capturing a material.

“Fluid” means any substance, such as a liquid or gas, that can flow, including bodily fluids, such as blood and blood plasma.

“Offset” means the relative position between two things that may otherwise be aligned but are not aligned with one another.

“Malleable” means capable of being shaped, altered or controlled by external forces or influences. “Malleable portion” means a portion of the filter device capable of switching between a constricted and an expanded position.

“Reversible” and “reversible vascular filter device” means a device that is capable of being eliminated after a period of time such that the device remains within a vessel but does not continue to filter.

“Vessel” means any vessel within a body, such as the human body, through which blood or other fluid flows and includes arteries and veins.

“Wire” means any type of wire, strand, stmt or structure, regardless of cross-sectional dimension (e.g., the cross-section could be circular, oval, or rectangular) or shape, and regardless of material, that may be used to construct a filter device as described herein. Some wires may be suitable for one or more of the embodiments but not suitable for others.

In accordance with one embodiment of the present invention, systems and methods are provided herein for capturing dislodged clots or debris (e.g., emboli) within a vessel using an implantable vascular filter device. The vascular filter device of the present invention may find use in capturing dislodged clots in, for instance, the vena cava. In various embodiments, the filter device can be bi-directional such that the device may be placed in a vessel in either direction to capture clots. In this way, the need associated with uni-directional filters to place them in a particular direction (e.g., along the blood flow) can be eliminated.

The vascular filter device of the present invention includes, in an embodiment, a single-piece reversible design. In other words, the reversible design of the vascular filter device of the present invention allows the device to remain within the vessel following implantation and the device can be deployed to not act as a filter, once such function is no longer necessary. By allowing the device to remain within the vessel following implantation, the vascular filter device of the present invention can reduce the likelihood of undesirable laceration, perforation or transection of the vessel walls associated with the removal process. The single-piece design may also ensure that the vascular filter device remains intact following implantation and that one of its components does not detach, as may occur if the vascular filter device were composed of more than one piece, which can damage the vessels or other organs or tissues downstream.

Since the vascular filter device is designed to be implanted within a vessel of a human or animal body, the vascular filter device may be made from a material that is biocompatible. The biocompatibility of the material may help minimize occurrence of adverse reactions due to implantation of the vascular filter device within a vessel. In some embodiments, the vascular filter device can be made entirely or partially from material that is bioresorbable, or biodegradable, or a combination thereof. In such instances, the vascular filter device may be entirely or partially absorbed by the vessel or may be degraded after a certain period of time has elapsed, and would eliminate the need for manual removal of the vascular filter device.

In an embodiment, the material from which the proximal portion of the vascular filter device may be formed includes metal, metal alloy, polymer, molded plastic, metal-polymer blend, or a combination thereof. The type of material may affect the strength and/or flexibility of the vascular filter device. Examples of suitable materials include stainless steel (e.g. type 304V), gold, platinum, tungsten, nickel-titanium alloy, Beta III Titanium, cobalt-chrome alloy, cobalt-chromium-nickel-molybdenum-iron alloy, Elgiloy, L605, MP35N, Ta-10W, 17-4PH, Aeromet 100, polyethylene terapthalate (PET), polytetraflouroethylene (PTFE), polyurethane (nylon) fluorinated ethylene propylene (FEP), polyurethane, polypropylene (PP), polyvinylchloride (PVC), polyether-ester, polyester, polyamide, elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA), silicones, polyethylene, polyether-ether ketone (PEEK), polyimide (PI), polyetherimide (PEI), tantalum, tungsten, or any other suitable material that is biocompatible and that is capable of being expanded in the manner described above. The vascular filter device may also include an anti-thrombogenic coating such as heparin (or its derivatives), urokinase, or PPack (dextrophenylalanine proline arginine chloromethylketone) to prevent thrombosis or any other adverse reaction from occurring at the site of insertion.

With reference to FIGS. 1A-1C, there is shown a bidirectional vascular filter device 100, in accordance with an embodiment of the present invention. Vascular filter device 100, as shown in FIG. 1A, includes, in one embodiment, an expandable framework or body 101 for secured placement of the device against a wall of a vessel. The framework 101, as illustrated, may be designed to expand, by an external force, from a collapsed state with sufficient force to secure the vascular filter device 100 against a vessel wall. To enhance security of the device 100 to the vessel wall, the framework 101 may include, in an embodiment, a securing or attachment mechanism (not shown). Examples of possible securing or attachment mechanisms can include a hook, pin, needle, prong, barb, wedge or any other securing or attachment mechanism adapted to adequately engage and secure the framework 101 to the vessel wall. In an embodiment, the securing mechanisms can be situated anywhere along the framework 101, as the present invention is not intended to be limited in this manner. In addition, an anti-inflammatory agent such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, mesalamine, or any suitable combination or mixture thereof may be applied to the securing mechanism to prevent inflammation or any other adverse reaction caused by the engagement of the securing mechanism along the vessel wall.

Vascular filter device 100 may also include opposing filters 102 and 103 positioned within pathway 104 of framework 101 for capturing clots within the fluid flow. Each of opposing filters 102 and 103, in an embodiment, may be defined by a plurality of malleable legs 110 and 111 (e.g., malleable wires or loops of malleable wire). The malleable legs, in one embodiment, may be designed so that they can be moved by an external force between a position where the legs are substantially against the framework 101 (e.g., when framework is substantially collapsed for delivering or when the framework is substantially expanded to establish a pathway therethrough) and a position where the plurality of legs approximate a substantially conical configuration. In an embodiment, the plurality of legs of the opposing filters 102 and 103 when approximating the substantially conical configuration can act to capture undesirable materials flowing through the vessel.

As shown in FIG. 1A, each of filters 102 and 103 may be attached at its open end to one end of framework 101, and can have its respective apex 105 and 106 positioned within the framework 101. Of course, should it be desired, each of filters 102 and 103 can be attached at its open end to any point along framework 101. In an embodiment, materials from which the malleable legs 110 and 111 of filters 102 and 103 can made include metal, metal alloy, polyglycolic acid, polymer, plastic, metal-polymer blend, or a combination thereof.

To capture undesirable materials such as clots, legs 110 of the filter 102 and legs 111 of filter 103, in an embodiment, may be configured so as to be sufficiently spaced from one another in order to capture undesirable materials of a certain or predetermined size. In that way, filter 102 or 103 can capture only undesirable materials of a certain or predetermined size, and direct the captured undesirable materials substantially along a predetermined or predefined path towards apex 105 or 106, respectively. The undesirable materials that may be too small to be captured by one or more of the legs, may be permitted to flow through the filter, as these materials can subsequently be eliminated by the natural process of the body (e.g., being degraded and absorbed). For example, as undesirable material within a fluid flow moves into framework 101, the undesirable material can be captured by at least one leg of filter 102 or 103. In an embodiment, due to the design of the legs, once the undesirable material is captured, the undesirable material can be directed along a predefined path toward the apex of the filter. Although described as being captured by one leg, it should be appreciated that the undesirable material having sufficient length can extend across two or more legs and be captured by multiple legs.

Each of the opposing filters 102 and 103 can also include a small opening at its apex 105 and 106 respectively. By providing an opening at the apex, should it be necessary to shape filters 102 and 103 into a desired shape for capturing clots, a shaping balloon 107, such as that shown in FIG. 1B can be directed, using any conventional means available in the art, through the opening in the respective apices of filters 102 and 103. Of course, shaping balloon 107 would need to be in a deflated state to be maneuvered through the opening of each apex. The shaping balloon 107 has been designed so that once its center 108 is substantially in a space between apices 105 and 106, shaping balloon 107 can be inflated to provide a shape having opposing conical portions, as shown in FIG. 1B, to shape filters 102 and 103 into the substantially conical configuration shown in FIG. 1A. For example, this shaping can be achieved by exerting force on the malleable legs 110 and 111 to move the legs from a position where the they may be substantially against the framework 101, that is, in a collapsed state, to a position where the legs 110 and 111 approximate a substantially conical configuration. Although shaping balloon 107 having opposing conical portions may be used, a shaping balloon with other geometric designs may alternatively be used.

Alternatively, expandable framework 101 may be compressed onto a deflated shaping balloon 107, and the assembly may be covered with a delivery sheath. Upon advancement into the vena cava to the site of interest, the sheath may be withdrawn, and the shaping balloon 107 may be inflated to provide framework 101 with a bi-directional filter configuration.

Although described herein as being shaped by an external force, it should be appreciated that the framework 101 and filters 102 and 103 can be provided with shape memory ability so that they can approximate a conical configuration upon expansion of the framework 101.

In an embodiment, when the legs 110 and 111 of the opposing filters 102 and 103 approximate the substantially conical configuration, the legs can act to capture undesirable materials flowing through the vessel. To the extent desired, the legs of one filter can be offset from the legs of opposing filter, so that should an undesirable material flowing through the framework escapes the legs of one filter, that escaping undesirable material can be captured by the legs of the opposing filter. The legs 110 and 111 of the opposing filters 102 and 103 can also be designed such that where undesirable materials are on the legs of both opposing filters 102 and 103, a fluid pathway still exists through the pathway 104 of the framework 101. In particular, as undesirable materials may accumulate near apex 105 of filter 102, a fluid pathway may still be available on the periphery of filter 102. Should undesirable materials bypass filter 102, and are captured by filter 103, since legs 111 of filter 103 are designed to direct the undesirable materials to the periphery of filter 103, a fluid pathway still exists through the center of filter 103.

It should be noted that filters 102 and 103 can be designed so that when they are no longer needed, the filters can be expanded against framework 101 to permit pathway 104 to be established through and along framework 101. To expand filters 102 and 103 against framework 101, looking now at FIG. 1C, a dilation balloon 109, such as an angioplasty dilation balloon, may be used. The dilation balloon 109, in an embodiment, can be designed so as to permit it to be directed through the opening in each apex of filters 102 and 103, using methods well known in the art. Once positioned within the opening of each apex, dilation balloon 109 can be inflated to expand the apex of each filter 102 and 103, along with the legs 110 and 111 filters 102 and 103. In that way, each filter may be pushed against the framework 101 and the walls of the vessel to permit reestablishment of a substantially tubular pathway 104 through the framework 101.

It should be noted that although shown as not connected to one another, should it be desired, filters 102 and 103 may be coupled to one another at their apices, and provided with an opening at such a juncture to permit the use of the shaping balloon 107 and dilation balloon 109.

FIGS. 2A-2D illustrate another bidirectional vascular filter device 200 of the present invention. Vascular filter device 200, as shown in FIG. 2A, includes, in one embodiment, a substantially tubular framework or body 201 that is substantially malleable, similar to framework 201 above. Framework 201, on an embodiment, may be capable of being expanded, by an external force, from a collapsed state to form a bidirectional design within a vessel (e.g., vena cava). Framework 201, in one embodiment, may be made from materials similar to those noted above for the other frameworks. To enhance secured placement of the framework 201 against the vessel walls at a site of interest, vascular filter device 200 may be provided barbs, hooks, or other similar attachment mechanisms to permit the framework 201 to securely position itself against the vena cava wall.

The framework 201 of the vascular filter device 200, as noted, can be provided with a bidirectional design, as shown in FIG. 2B, by permitting opposing end portions of the framework 201 to expand to form opposing filters 202 and 203. To shape opposing ends of the framework 201 into filters 202 and 203 for capturing clots, a shaping balloon 204, such as that shown in FIG. 2C can be used. Shaping balloon 204, in an embodiment, can be provided with a design to permit it to be directed, using any conventional means available in the art, into pathway 205 of framework 201 and span both filters 202 and 203. Of course, shaping balloon 204 would need to be in a deflated state to be maneuvered into pathway 205. Once the shaping balloon 204 has been positioned within pathway 205, shaping balloon 204 can be inflated to provide a shape with an opposing conical portions, as shown in FIG. 2C to shape filters 202 and 203 into the shape shown in FIG. 2B. Alternatively, expandable framework 201 may be compressed onto a deflated shaping balloon 204, and the assembly may be covered with a delivery sheath. Upon advancement into the vena cava to the site of interest, the sheath may be withdrawn, and the shaping balloon 204 may be inflated to provide framework 201 with a bi-directional filter configuration.

It should be appreciated that although shaping balloon 204 having opposing conical shapes may be used, a shaping balloon with other geometric designs may alternatively be used.

As framework 201 may be malleable, in order to enhance the filtering function of filters 202 and 203, vascular filter device 200 may be provided with extension arms 206 or struts. In an embodiment, these arms may be attached to framework 201, by any methods or mechanisms known in the art, towards the end portions (e.g., proximal and distal) of the framework 201. Arms 206, in one embodiment, may be independent of one another and may be positioned circumferentially about framework 201 and in a substantially parallel direction relative to axis A of vascular filter device 200. In that way, when the opposing filters 202 and 203 are formed, arms 206 can approximate a conical shape of the opposing filters within pathway 205. The presence of the arms 206 at each filter, in one embodiment, can enhance the structural integrity of the filters 202 and 203 and can enhance the ability of these filters to capture clots within the fluid flow.

Filters 202 and 203, as with the filters above, can be designed so that when they are no longer needed, framework 201 can be expanded against the vena cava walls to permit pathway 205 to be reestablished through and along framework 201. To expand framework 201 against a vessel wall, looking now at FIG. 2D, a dilation balloon 207, such as an angioplasty dilation balloon, may be directed into pathway 205 of framework 201, using methods well known in the art. Once positioned within pathway 205, dilation balloon 207 may be inflated to expand middle portion 208 of framework 201, which middle portion 208 may previously not have been in an expanded state relative to filters 202 and 203. Expanding the middle portion 208 can occur along with the remaining portions of framework 201, including filters 202 and 203, to push the framework 201 against the walls of the vessel and permit reestablishment of pathway 205.

In operation, to prepare the vascular filter device for insertion in the body, a user can initially collapse the vascular filter device for insertion into a delivery mechanism, for example, a catheter. Once loaded into a delivery mechanism, the delivery mechanism may be inserted into the body, and advanced along a vessel within the body (e.g. the inferior vena cava) to a site of interest for implantation. The filter device may then be removed from within the delivery mechanism and permitted to expand. The expansion of the device or framework allows the device to engage the wall of the vessel, as shown in FIGS. 1-2, and to minimize subsequent movement of the device from the site of implantation. When engaging the vessel wall, securing mechanisms on the framework of the device can secure the framework against the vessel wall. Upon expansion of the device or framework, at least one filter having a substantially conical shape may be formed. With the vascular filter device deployed and engaged within the vessel, blood clots and other debris can subsequently be captured within the filter or filters.

Once the filtering function is no longer necessary, it may be desirable to reverse (i.e., eliminate) the filter or filters and reestablish the pathway through the device. Reversal of the filtering function may involve elimination of the filters manually. Manual removal may include, for example, advancing into the vena cave a device capable of severing the filter or filter formation element, locating the filter or filter formation element, and severing the filter or filter formation element. Severing the filter or filter formation element may involve cutting the wires or the mechanism holding the filter in place. In another embodiment, the filter or filter formation element can be removed by permitting their resorption or degradation over a period of time.

A method of manufacturing a filter in accordance with the present invention is also provided. In some embodiments, metals, including superelastic metals, may have a hardened state. In a hardened state, the metal may be made to be self-expanding and spring-like. In other embodiments, metals, including superelastic metals, may have an annealed state. In an annealed state, the metal may be made to be deformable and malleable. A filter framework, in accordance with one embodiment, may be manufactured from a single tube. The single tube may, in an embodiment, be in an annealed state, where it is soft and malleable. The tube, for example, can then be cut using laser or other methods known in the art to yield the desired framework. Once the desired framework is produced, the malleable framework can, in an embodiment, be expanded mechanically using, for instance, a dilation balloon or other dilation device to form a filter or “butterfly” configuration. Once expanded, the tube may remain in the “butterfly” configuration. While in this configuration, the framework may, in one embodiment, be treated and processed by first heating the framework to a substantially high temperature and then quenching the framework in a low temperature fluid bath to harden the entire filter and produce spring-like properties. It should be appreciated that other methods known in the art may also be used to provide spring-like properties to the framework.

In some embodiments, it may be desired that certain portions, such as the filter arms and/or the middle portion, of the framework be malleable. Where malleability is desired, portions of the framework may be treated and processed by first heating the desired portions, and then letting the desired portions cool at a substantially slower rate, for instance, in the air. In one embodiment, the filter arms and the middle portion may be made malleable by reheating and allowing room cooling of these areas. The process of heating followed by air cooling is able to anneal and soften the filter arms and the middle portion making them malleable. Of course, other methods known in the art can also be used to treat and process the framework so as to provide malleable characteristics to the desired portions.

It should be appreciated, that although described as being formed from a single tube, the filter may be formed from multiple components that can be joined together to form a framework.

While the invention has been described in connection with the specific embodiments thereof, it will be understood that it is capable of further modification. Furthermore, this application is intended to cover any variations, uses, or adaptations of the invention, including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as fall within the scope of the appended claims. 

1. A bi-directional filter device comprising: an expandable framework for secured placement of the device against a wall of a vessel; a pathway extending through the expandable framework; and opposing filters situated within the pathway, each defined by a plurality of malleable legs capable of being moved by an external force between a position where the plurality of legs are substantially against the framework and a position where the plurality of legs approximate a substantially conical configuration.
 2. The device of claim 1, wherein the framework includes an attachment mechanism to enhance secured placement of the device against the wall of the vessel.
 3. The device of claim 1, wherein the plurality of legs of the opposing filters when approximating the substantially conical configuration can act to capture undesirable materials flowing through the vessel.
 4. The device of claim 1, wherein the plurality of legs of the opposing filters are sufficiently spaced apart to capture undesirable materials of a predetermined size.
 5. The device of claim 1, wherein the legs of one filter are offset from the legs of opposing filter, so that should an undesirable material flowing through the framework escapes the legs of one filter that escaping undesirable material can be captured by the legs of the opposing filter.
 6. The device of claim 1, wherein the legs of the opposing filters are designed to direct the undesirable materials captured thereon along a predetermined path.
 7. The device of claim 6, wherein the legs of the opposing filters are designed such that where undesirable materials are on the legs of both opposing filters, a fluid pathway still exists through the pathway of the framework.
 8. The device of claim 1, wherein the plurality of legs when positioned substantially against the framework can allow the framework to be in one of a collapsed position, or an expanded position that can establish a substantially tubular pathway through the framework
 9. The device of claim 1, wherein the external force acting on the plurality of legs is a balloon catheter designed to extend through the framework to move the plurality of legs.
 10. A method for capturing an undesirable material, comprising: placing, within a vessel at a site of interest, a framework having a set of malleable legs coupled to a proximal portion and a set of malleable legs coupled to a distal portion of the framework; exerting an external force within the framework so as to permit the plurality of legs at the proximal portion and the distal portion of the framework to approximate opposing substantially conical configurations to act as opposing filters; continuing to exert the external force within the framework to secure the expandable framework against a wall of the vessel; and allowing undesirable material to flow into the framework to permit the undesirable material to be captured by the legs of at least one of the opposing filters.
 11. The method of claim 10, wherein the step of exerting includes extending a balloon catheter through the framework to move the plurality of legs.
 12. The method of claim 10, wherein the step of allowing includes directing the captured undesirable material along a predetermined path on the plurality of legs.
 13. The method of claim 10, wherein the step of allowing includes permitting an undesirable material flowing through the framework that escapes the legs of one filter to be captured by the legs of the opposing filter.
 14. The method of claim 13, wherein the step permitting includes maintaining a fluid pathway through the framework when undesirable materials exist on both opposing filters.
 15. The method of claim 10 further comprising pushing the plurality of legs of the opposing filters from a conical configuration against the framework to establish a substantially tubular pathway through the framework. 